1. 46 March 2011 • ROADS&BRIDGES
A Century in
the remaking
Famous route in Oregon benefits from 3-D milling
I
n Oregon, Century Drive Highway is
a big deal. How big? It is important
enough to merit a Wikipedia entry.
The route winds its way through a dark-
green pine forest and leads to the Cascade
High Lakes recreational area. In the warmer
months, traffic can get quite heavy, including
a fair number of bicycle riders enjoying the
scenery along the way. Until recently, bicyclists
were precariously relegated to the edge of the
road while four-wheel traffic dangerously
whizzed past on their way to a number of
lakes, campgrounds and small resorts at the
foot of the Cascade Mountains.
In 2007, the Western Federal Lands
Highway Division of the Federal Highway
Administration (FHWA) put out a bid to have
10.5 miles of the forest highway resurfaced, as
well as widened and realigned in some areas.
Because 5-ft-wide paved shoulders were added
to accommodate bicycles, the project was
jokingly referred to as the $7 million bike path.
However, the FHWA would soundly argue that
the increased traffic combined with the age
of the two-lane road called for the work to be
completed, regardless of the enhanced safety
for bicyclists. The finished paved width of
the highway is 32 ft, including the paved 5-ft
shoulders to accommodate cyclists.
Burning the stakes
Tidewater Contractors, based in Brook-
ings, Ore., won the project bid. As the general
contractor, Tidewater was responsible for
this two-season project, which started in May
2008. The company has been in business
since 1978 and has a focus on highway con-
struction with adjunct ready-mix and asphalt
paving operations.
Tidewater Contractors’ first step was to
check the existing survey control network on
the national forest road project. These are the
ASPHALT MILLING
By Jeff Winke
Contributing Author

2. ROADSBRIDGES.com 47
ground surface points that were used for
survey staking and grade control.
“We used a Trimble SPS930 Universal
Total Station to verify the points and con-
firm the quantities,” stated Mark Mann,
project engineer with Tidewater Contrac-
tors. “This is all necessary prep work for
creating an accurate 3-D road model.”
The original ground model and
staking note data in digital format was
provided by the FHWA. The original data
and Mann’s data collected at the site
were used for creating the 3-D design
model for the project.
“I began by building a 3-D road
model for the project that we use
for both survey stakeout and grade
checking—which is something I do with
all road projects,” Mann said. “I’ve been
working with Trimble survey equipment
since 1999 and have been taking the
digital design to the field for use directly
with the survey equipment and grade
checking to construct a project, which
provides us with a pretty substantial
payoff by itself.”
Additionally, Tidewater examined
the scope of the work to be performed
and saw beneficial opportunities
for machine control. The company
developed a “value-engineering
proposal” for the project to include
the use of 3-D machine control. The
proposal, which was accepted by the
FHWA, specified that Tidewater and
the government would share in cost
savings due to the reduced survey stak-
ing reaped by the technology.
“We didn’t tear up any pavement
in 2008 because it required that we
replace it with temporary asphalt, so we
spent the first season installing culverts,
building walls . . . most of the work
outside the existing pavement,” said
Mann. “All the major roadwork needed
to be completed by Sept. 15, 2009,
so that gave us a very short season to
complete all the work through the
finished paving.”
In addition to facing a short
construction season, the work also
was being completed during the high
recreational period when the road use is
at its heaviest.
“We needed to be extremely produc-
tive,” said Mann. “To do this, we decided
to implement machine-control technol-
ogy to eliminate a good deal of the
survey staking and ensure the highest
finished-paving quality—this was the
first project where we implemented
machine control.”
Precise set of teeth
Mann had been researching 3-D
machine control for several years,
attending user conferences and studying
the trade magazines.
“I attended a session on 3-D milling
[in 2009],” stated Mann. “This was right
before we were to begin tackling the
substantial amount of milling on the
South Century Drive project.”
In the session, Mann learned that a
grade-control system can be installed
on milling machines (cold planers) for
highly accurate milling at variable depth
and slope without stringlines.
Mann continued, “I spoke with the
3-D milling expert at the conference and
described the project we were about to
embark on. They felt it would be a good
match for the 3-D milling system.”
Local experts agreed that the South
Century Drive Highway project was
well-suited for “intelligent 3-D mill-
ing” technology due to the advantages
of variable-depth milling. With a
traditional 2-D control system, the
machine mills to a constant depth and
essentially copies the old surface. With a
grade-control system on the cold planer,
the 3-D control system varies its mill
depth according to the 3-D design. It
is designed to match the design profile
with ±5-mm accuracy.
Throughout the entire length of the
road, the design called for the existing
pavement and base to be milled at 5-in.
and 8-in. depths.
“We saved a considerable amount of
time and additional work by using [a
grade-control system] and milling to the
design profile at variable depths from
3 to 12 in.,” Mann stated. “It increased
our production, since we milled only
what was needed. And we used less
asphalt during paving, since there
were no low spots or unevenness that
required filling in.”
Mann added, “With fixed-depth mill-
ing, the machine does not cut to design,
so further grading work is required and
you don’t know where the design line
is; you often cut more or less than is
required to achieve grade. This calls for
another cut/fill process with a grader.
On the other hand, with 3-D milling,
you’re milling to a design profile and
eliminating the cut/fill process by the
grader as is required in fixed-depth mill-
ing. This is the critical point that without
3-D milling technology would not be
practical: We were milling to the design
profile, not a fixed depth.”
With the accuracy of the milling,
the grading of the subgrade was more
efficient, and Tidewater Contractors
Tidewater Contractors received a smoothness bonus of $127,397, and the Western
Federal Lands Highway Division reported that the roadbuilder achieved the smoothest
ride since they started using the International Roughness Index.

3. 48 March 2011 • ROADS&BRIDGES
was able to mill and finish grade up to
12,000 sq yd of road surface at a 3 to 12
in. depth in one day.
The time-saving advantage with the
machine-control system helped over-
come considerable delays caused by a
subsequent problem with a rock source
for the project.
“In our testing we discovered that
Throughout the entire length of the road, the design called for the existing pavement and base to be milled at 5- and 8-in. depths. “We
saved considerable amount of time and additional work by using [a grade-control system] and milling to the design profile at variable
depths from 3 to 12 in.,” said Mark Mann, project engineer with Tidewater Contractors.
Circle 775

4. ROADSBRIDGES.com 49
the crushed volcanic basalt rock we
were planning to use in the asphalt mix
had degraded over winter,” Mann said.
“It’s very rare to see this happen, but
we couldn’t use the stockpile percent-
ages per the original mix design, which
required crushing additional aggregate.”
The issue was discovered when Tide-
water found that in its initial test strips
they could not achieve compaction.
“This is a national standard Super-
pave mix design, and maintaining
aggregate gradations on the mix design
is crucial,” stated Mann. “The FHWA
recognized that the aggregate problems
were not our fault.” But the snafu did
cause delay while Tidewater waited
for additional aggregate to be crushed,
tested and stockpiled.
“There’s no question in my mind that
had it not been for the use of machine
control that this project would not have
been completed in 2009. It would have
slipped into a third year, which would
have had a substantial cost impact to
the government,” Mann concluded. “We
estimate that the use of 3-D machine
control for milling and grading saved us
11 days on the project.”
Like magic
With the challenges of a brief season,
the variable-depth milling challenge
and the issues with the crushed rock,
Tidewater Contractors was still able to
pull the rabbit out of the hat.
“We finished the last of the paving
and the pavement striping in snow flur-
ries that led into five days of continuous
snow,” Mann stated. “At the time, the
project was behind schedule due to
[FHWA] change orders and paving rock
issues, but we’re pleased that by using
technology we prevented work carryover
into another season.”
As Mann looked back on the project,
he pointed to several accomplishments:
“First, we received a smoothness bonus
of $127,397, and the Western Federal
Lands Highway Division reported that
we achieved the smoothest ride since
they started using the IRI [International
Roughness Index] method for calculat-
ing smoothness. In our case, we had
super-accurate milling and consistent,
accurate subgrades, which made it pos-
sible to finish with our bonus-winning
smooth surface.
“I was also very pleased with the
support we received from our Trimble
dealer. They came out while the
project was ongoing and installed the
systems and tailored the machines to
the project and the work styles of the
operators without interruption to the
work in progress. Once the mill was
calibrated and field-tested, we didn’t
have to touch it again. And finally,
we created a road with a smooth ride
that’s safe for everyone heading up to
the Cascade High Lakes area—which is
a great feeling.” R&B
Winke is with Jeff Winke Consultancy.
For more information about this topic,
check out the Asphalt Zone at
www.roadsbridges.com.
Circle 776
Concrete demolition and repair is hard, noisy, dirty work—especially if
you’re still removing concrete with jack hammers. With Jetstream’s
X-Series hydro-demolition capabilities, we make the work easier, quieter
and cleaner for you and your crew.
For efficient, effective concrete removal, Jetstream
waterblasters deliver controlled high-pressure water
up to 40,000 psi. Now you can remove overlay
without destroying the reinforcement such as rebar,
brackets and bolts. And you won’t have to worry
about causing micro-fractures in the remaining
concrete that could be a problem down the line.
©2011 Jetstream of Houston, LLC
Come see us in booth #9633 at the ConExpo-
Con/Agg show in Las Vegas, March 22-26!